Penetrable cap

ABSTRACT

The present invention relates to a cap which can form an essentially leak-proof seal with an open-ended vessel capable of receiving and holding fluid specimens or other materials for analysis. To minimize potentially contaminating contact between a fluid sample present in the vessel and humans or the environment, the present invention features a cap having a frangible seal which is penetrable by a plastic pipette tip or other fluid transfer device. The cap further includes filtering means for limiting dissemination of an aerosol or bubbles once the frangible seal has been pierced. The filtering means is positioned between the frangible seal and retaining means. The retaining means is positioned on the cap above the filtering means and may be used to contain the filtering means within the cap. The retaining means may be comprised of a material which is penetrable by a fluid transfer device.

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/274,493, filed Mar. 9, 2001, the contents of whichare hereby incorporated by reference herein.

FIELD OF THE INVENTION

[0002] The present invention relates to caps for use in combination withfluid-holding vessels, such as those designed to receive and retainbiological specimens for clinical analysis, patient monitoring ordiagnosis. In particular, the present invention relates to a cap whichis penetrable by a fluid transfer device used to transfer fluids to orfrom a fluid-holding vessel, where the vessel and cap remain physicallyand sealably associated during a fluid transfer.

INCORPORATION BY REFERENCE

[0003] All references referred to herein are hereby incorporated byreference in their entirety. The incorporation of these references,standing alone, should not be construed as an assertion or admission bythe inventors that any portion of the contents of all of thesereferences, or any particular reference, is considered to be essentialmaterial for satisfying any national or regional statutory disclosurerequirement for patent applications. Notwithstanding, the inventorsreserve the right to rely upon any of such references, whereappropriate, for providing material deemed essential to the claimedinvention by an examining authority or court. No reference referred toherein is admitted to be prior art to the claimed invention.

BACKGROUND OF THE INVENTION

[0004] Collection devices are a type of cap and vessel combinationcommonly used for receiving and storing biological specimens fordelivery to clinical laboratories, where the specimens may be analyzedto determine the existence or state of a particular condition or thepresence of a particular infectious agent, such as a virus or bacterialmicroorganism. Types of biological specimens commonly collected anddelivered to clinical laboratories for analysis include blood, urine,sputum, saliva, pus, mucous and cerebrospinal fluid. Since thesespecimen-types may contain pathogenic organisms, it is important toensure that collection devices are constructed to be substantiallyleak-proof during transport from the site of collection to the site ofanalysis. This feature of collection devices is especially importantwhen the clinical laboratory and the collection facility are remote fromone another, increasing the likelihood that the collection device willbe inverted or severely jostled during transport and potentiallysubjected to substantial temperature and pressure fluctuations.

[0005] To prevent specimen leakage, and possible contamination of thesurrounding environment, collection device caps are typically designedto be screwed, snapped or otherwise frictionally fitted or welded ontothe vessel component, thereby forming a substantially leak-proof sealbetween the cap and the vessel. In addition to preventing fluid specimenfrom leaking, a substantially leak-proof seal formed between the cap andthe vessel components of a collection device may also aid inameliorating exposure of the specimen to potentially contaminatinginfluences from the immediate environment. This aspect of a leak-proofseal is important for preventing the introduction of contaminants intothe collection device that could alter the qualitative or quantitativeresults of an assay.

[0006] While a leak-proof seal should prevent specimen seepage duringtransport, the actual removal of the cap from the vessel prior tospecimen analysis presents another potential opportunity forcontamination. When removing the cap, specimen which may have collectedon the underside of the cap during transport could come into contactwith a clinician, possibly exposing the clinician to a harmful pathogenpresent in the fluid sample. And if the specimen is proteinaceous ormucoid in nature, or if the transport medium contains detergents orsurfactants, then a film or bubbles could form around the mouth of thevessel during transport which could burst when the cap is removed fromthe vessel, thereby disseminating specimen into the testing environment.Another risk associated with cap removal is the potential for creating acontaminating aerosol which may lead to false positives or exaggeratedresults in other specimens being simultaneously or subsequently assayedin the same general work area through cross-contamination. It is alsopossible that specimen residue from one collection device, which mayhave been inadvertently transferred to a gloved hand of a clinician,will come into contact with specimen from another collection devicethrough routine or careless removal of caps and handling of thecollection devices.

[0007] Concerns with cross-contamination are especially acute when theassay being performed involves nucleic acid detection and includes anamplification procedure such as the well known polymerase chain reaction(PCR), or a transcription-based amplification system such astranscription-mediated amplification (TMA). (A review of severalamplification procedures currently in use, including PCR and TMA, isprovided in HELEN H. LEE ET AL., NUCLEIC ACID AMPLIFICATION TECHNOLOGIES(1997).) Since amplification is intended to enhance assay sensitivity byincreasing the quantity of targeted nucleic acid sequences present in aspecimen, transferring even a minute amount of pathogen-bearing specimenfrom one vessel, or target nucleic acid from a positive control sample,to another vessel containing an otherwise negative specimen could resultin a false-positive result.

[0008] To minimize the potential for creating contaminating specimenaerosols, and to limit direct contact between specimens and humans orthe environment, it is desirable to have a collection device cap whichcan be penetrated by a fluid transfer device (e.g., a pipette tip whichcan be used with an air displacement pipette) while the cap remainsphysically and sealably associated with the vessel. The material andconstruction of the penetrable aspect of the cap should facilitate theventing of air displaced from the interior space of the collectiondevice to ensure accurate fluid transfers and to prevent a rapid releaseof aerosols as the fluid transfer device is being inserted into orwithdrawn from the collection device. And, because air is vented fromthe interior space of the collection device after the cap has beenpenetrated, it would be particularly helpful if means were included forminimizing aerosol release through the cap once it was penetrated by thefluid transfer device. Also, to limit the amount of potentiallycontaminating fluid present on the exterior of the fluid transfer deviceafter it is has been withdrawn from the collection device, it would beadvantageous if the cap also included means for wiping or absorbingfluid present on the outside of the fluid transfer device as it is beingwithdrawn from the collection device. To prevent damage to the fluidtransfer device which could affect its ability to predictably andreliably dispense or draw fluids, and to facilitate its use in manualpipetting applications, the cap should also be designed to limit theforces necessary for the fluid transfer device to penetrate the cap.Ideally, the collection device could be used in both manual andautomated formats and would be suitable for use with disposable pipettetips made of a plastic material.

[0009] Collection device caps which can be penetrated by a fluidtransfer device will have other advantages, as well, including thetime-savings resulting from clinicians not having to manually removecaps from vessels before retrieving sample aliquots from the collectiondevices for assaying. Another advantage of penetrable collection devicecaps would be the reduction in repetitive motion injuries suffered byclinicians from repeatedly unscrewing caps.

SUMMARY OF THE INVENTION

[0010] The present invention solves the potential contamination problemsassociated with conventional collection devices by providing apenetrable cap for use with a vessel component of a collection devicewhich includes: (i) a closed side wall having an inner surface, an outersurface, a top surface and a bottom surface; (ii) attachment means forfixing the cap to an open end of the vessel in sealing engagement; (iii)a ledge which extends in a radial and inward direction from an innersurface of the side wall of the cap and has an end surface which definesan aperture sized to receive a fluid transfer device, where the innersurface of the side wall of the cap and a top surface of the ledgedefine a first bore; (iv) a frangible seal for preventing the passage ofa fluid from an interior space of the vessel into the first bore whenthe cap is fixed to the vessel in sealing engagement, where the seal isaffixed to either the top surface or a bottom surface of the ledge; (v)filtering means for impeding or preventing the release of an aerosol orbubbles from the interior space of the vessel to the atmosphere, wherethe filtering means is positioned substantially within the first bore;and (vi) retaining means for containing the filtering means within thefirst bore. (A “closed side wall” is one which lacks fully exposed endsurfaces.) The retaining means is preferably affixed to a top wall ofthe cap. The side wall, the flange and the ledge of the cap are moldedfrom a plastic material and preferably form a unitary piece.

[0011] In an alternative and preferred embodiment, the penetrable capincludes a skirt which depends from the bottom surface of the ledge,where an inner surface of the skirt defines a second bore having adiameter or width smaller than that of the first bore. The skirt may beincluded inter alia to further prevent a fluid from leaking from theinterior of the vessel when the cap is fixed to the vessel in sealingengagement. (By “sealing engagement” is meant touching contact betweensolid surfaces which is intended to prevent or impede the passage of afluid.) An outer surface of the skirt preferably includes a seal beadwhich is in frictional contact with an inner surface of the vessel. Withthis embodiment, the frangible seal may be affixed to either the topsurface of the ledge or to a bottom surface of the skirt. The side wall,the flange, the ledge and the skirt of the cap of this embodiment aremolded from a plastic material and preferably form a unitary piece.

[0012] In another embodiment of the present invention, the retainingmeans is a second frangible seal. The second frangible seal may comprisethe same or a different material than the frangible seal affixed to thetop or bottom surface of the ledge, or to the bottom surface of theskirt. Both seals are penetrable by a fluid transfer device with theapplication of moderate manual force and each seal preferably comprisesa foil.

[0013] In still another embodiment of the present invention, theretaining means comprises a foil ring having a centrally located holewhich is sized to receive a fluid transfer device and which issubstantially axially aligned with the first bore and the second bore,if present. The diameter or width of this hole is smaller than thediameter or width of a filter contained within the first bore so thatthe foil ring can function to contain the filter within the cap. Thefoil ring of this embodiment may be affixed to the top wall of the capby means of an adhesive or by means of a plastic liner which has beenapplied to the foil ring and which can be welded to the surface of thetop wall of the cap.

[0014] In yet another embodiment of the present invention, the retainingmeans includes a plastic disc having a hole formed therein which issized to receive a fluid transfer device and which is substantiallyaxially aligned with the first bore and the second bore, if present. Theretaining means of this embodiment functions to contain a filter withinthe first bore. The disc may be affixed to the top wall of the cap orthe top wall may be adapted to include a seat for receiving the disc in,for example, a frictional or snap fit.

[0015] In a further embodiment, the retaining means comprises aremovable seal which is designed to limit exposure of a filter toenvironmental contaminants and may include a tab for easy removal priorto penetrating the cap. Because this seal may be removed prior topenetration of the cap, it is not a requirement that this particularretaining means be comprised of a frangible material which can bepierced by a fluid transfer device applying moderate manual force. Sincethe removable seal can function to protect the filter against externalcontaminants during shipping, the removable seal may be applied, forexample, to the fixed disc described above for retaining the filterwithin the first bore.

[0016] In still another embodiment, the cap is provided as part of acollection device which includes a vessel for containing fluids. Whenprovided as a part of a collection device, the cap preferably includesthe skirt feature described above, which is positioned adjacent to aninner surface of an open end of the vessel to impede the passage of afluid from the interior space of the vessel to the environment outsideof the collection device. Including a seal bead on an outer surface ofthe skirt further facilitates this objective by increasing the pressurewhich is exerted by the skirt on the inner surface of the vessel. Thecollection device may contain, for example, a dry powder, pellets ofchemical reagents, buffers, stabilizers, or a transport medium forpreserving a specimen while it is being shipped from a collectionlocation to a site for analysis. The collection device may also beprovided in packaged combination with a specimen retrieval device (e.g.,a swab) for obtaining a specimen from a human, animal, water,environmental, industrial, food or other source. Instructional materialsmay additionally be included with the collection device which detailproper use of the collection device when obtaining or transporting aspecimen or appropriate techniques for retrieving a fluid sample fromthe collection device at the site of analysis. When in packagedcombination, the recited items are provided in the same container (e.g.,a mail or delivery container for shipping), but do not need to be per sephysically associated with one another in the container or combined inthe same wrapper or vessel within the container.

[0017] In yet another embodiment, the cap can be used in a method forretrieving a fluid substance from the vessel component of a collectiondevice with a plastic pipette tip for use with an air displacementpipette. When the cap is penetrated by the pipette tip, air passagewaysare formed between the pipette tip and the frangible seal or seals ofthe cap, thereby facilitating the venting of air from within the vessel.After fluid is removed from the collection device, at least some portionof the fluid sample may be exposed to amplification reagents andconditions permitting a targeted nucleic acid sequence which may bepresent in the fluid sample to be amplified. Various amplificationprocedures, and their associated reagents and conditions, are well knownto those skilled in the art of nucleic acid diagnostics.

[0018] In still another embodiment, a method is provided for removing afluid substance contained in a closed system comprising a cap and afluid-holding vessel. In addition to the cap and vessel components, thephrase “closed system” is used herein to refer to a cap that is fixed toa vessel in sealing engagement to prevent the fluid contents of thesystem from escaping into the surrounding environment. The methodincludes penetrating first and second frangible seals affixed to the capwith a fluid transfer device, where the second seal is axially alignedbelow the first seal. Penetration of the first and second seals by thefluid transfer device results in the formation of air passagewaysbetween the seals and the fluid transfer device which aid in venting airfrom the interior space of the system. The fluid transfer device ispreferably a plastic pipette tip for use with an air displacementpipette. In a preferred mode, the method further includes passing thefluid transfer device through a filter contained within the cap andinterposed between the first and second seals.

[0019] Once fluid has been removed from the system in this method, someor all of the fluid sample may be exposed to amplification reagents andconditions permitting a targeted nucleic acid sequence which may bepresent in the fluid sample to be amplified. As noted above, a varietyof amplification procedures are well known to those skilled in the artof nucleic acid diagnostics, and appropriate reagents and conditions foruse with any of these amplification procedures could be determinedwithout engaging in undue experimentation.

[0020] In yet a further embodiment of the present invention, a method isprovided for depositing substances into the collection devices and otherclosed systems of the present invention by means of a substance transferdevice capable of transporting fluids (e.g., specimen or assay reagents)or solids (e.g., particles, granules or powders). This embodiment of thepresent invention is particularly useful for diagnostic assays which canbe performed in a single reaction vessel and where it is desirable tomaintain the contents of the vessel in a substantially closedenvironment. The steps of this embodiment are similar to those of otherpreferred methods described herein, except that one or more substanceswould be deposited into the vessel component rather than retrieving afluid sample contained therein.

[0021] The methods of the presently claimed invention may be performedmanually or adapted for use with a semi-automated or fully automatedinstrument. Examples of instrument systems which could be readilyadapted for use with the collection devices or other closed systems ofthe present invention include those sold under the trade names of DTS400 (detection only) and DTS 1600 (amplification and detection) byGen-Probe Incorporated of San Diego, Calif., which represent embodimentsof instrument systems disclosed by Acosta et al., “Assay Work Station,”U.S. Pat. No. 6,254,826, and those disclosed by Ammann et al.,“Automated Process for Isolating and Amplifying a Target Nucleic AcidSequence,” U.S. Pat. No. 6,335,166, both of which enjoy common ownershipherewith.

[0022] These and other features, aspects, and advantages of the presentinvention will become apparent to those skilled in the art afterconsidering the following detailed description, appended claims andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is an exploded perspective view of the cap and vesselcomponents of a preferred collection device of the present invention.

[0024]FIG. 2 is an enlarged top plan view of the core cap of FIG. 1.

[0025]FIG. 3 is an enlarged bottom view of the core cap of FIG. 1.

[0026]FIG. 4 is an enlarged partial section side view of the collectiondevice of FIGS. 1-3 (showing core cap only), taken along the 4-4 linethereof.

[0027]FIG. 5 is an enlarged partial section side view of anothercollection device according to the present invention.

[0028]FIG. 6 is an enlarged section side view of the cap of FIG. 1.

[0029]FIG. 7 is an enlarged section side view of another cap accordingto the present invention.

[0030]FIG. 8 is an enlarged section side view of a frangible sealaccording to the present invention.

[0031]FIG. 9 is an enlarged section side view of another frangible sealaccording to the present invention.

[0032]FIG. 10 is an enlarged top plan view of the core cap and filter ofFIG. 1.

[0033]FIG. 11 is a top plan view of the cap of FIGS. 6 and 7 showingperforations in the frangible seal.

[0034]FIG. 12 is an enlarged top plan view of a further cap according tothe present invention.

[0035]FIG. 13 is an enlarged section side view of yet another capaccording to the present invention.

[0036]FIG. 14 is a top plan view of the cap of FIG. 13.

[0037]FIG. 15 is an enlarged section side view of still another capaccording to the present invention.

[0038]FIG. 16 is a top plan view of the cap of FIG. 15.

[0039]FIG. 17 is a partial section side view of the collection device ofFIG. 1, after it has been penetrated by a fluid transfer device.

[0040]FIG. 18 is a top plan view of the cap and fluid transfer device ofFIG. 17.

DETAILED DESCRIPTION OF THE INVENTION

[0041] While the present invention may be embodied in a variety offorms, the following description and accompanying drawings are merelyintended to disclose some of these forms as specific examples of thepresent invention. Accordingly, the present invention is not intended tobe limited to the forms or embodiments so described and illustrated.Instead, the full scope of the present invention is set forth in theappended claims.

[0042] With reference to the figures, preferred caps 30A-E of thepresent invention are shown alone or in combination with a vessel 20which can be used for receiving and storing fluid specimens forsubsequent analysis, including analysis with nucleic acid-based assaysor immunoassays diagnostic for a particular pathogenic organism. Whenthe desired specimen is a biological fluid, the specimen can be, forexample, blood, urine, saliva, sputum, mucous or other bodily secretion,pus, amniotic fluid, cerebrospinal fluid or seminal fluid. However, thepresent invention also contemplates materials other than these specificbiological fluids, including, but not limited to, water, chemicals andassay reagents, as well as solid substances which can be dissolved inwhole or in part in a fluid milieu (e.g., tissue specimens, stool,environmental samples, food products, powders, particles and granules).The vessel 20 is preferably capable of forming a substantiallyleak-proof seal with the cap 30A-E and can be of any shape orcomposition, provided the vessel is shaped to receive and retain thematerial of interest (e.g., fluid specimen or assay reagents). Where thevessel 20 contains a specimen to be assayed, it is important that thecomposition of the vessel be essentially inert so that it does notsignificantly interfere with the performance or results of an assay. Apreferred vessel 20 is formed of polypropylene and has a generallycylindrical shape which measures approximately 13 mm×82 mm.

[0043] As illustrated in the figures, particularly preferred caps 30A-Eof the present invention include an integrally molded core structure 31A(referred to herein as the “core cap”) which comprises: (i) a generallycylindrical side wall 35; (ii) a flange 36 depending from a bottomsurface 37 of the side wall and having an inner surface 38 adapted togrip an outer surface 21 of a generally cylindrical side wall 22 of anopen-ended vessel 20; (iii) a ledge 39 extending radially inwardly froman inner surface 40 of the side wall 35 above the flange 36; and (iv) agenerally cylindrical skirt 41 depending from a bottom surface 42 of theledge in a substantially parallel orientation to the flange. The innersurface 40 of the side wall 35 and a top surface 43 of the ledge 39define a first bore 44, as shown in FIG. 4, which is sized to receive afilter 33, as shown in FIGS. 6 and 7, that may be frictionally fitted orotherwise immobilized within the first bore. In a preferred embodiment,the ledge 39 aids in retaining the filter 33 within the first bore 44during penetration of the cap 30A-E by a fluid transfer device. Theledge 39 can also function as a surface for affixing a frangible seal32, as depicted in FIG. 6. An inner surface 45 of the skirt 41 beneaththe top surface 43 of the ledge 39 defines a second bore 46 which issmaller in diameter than the first bore 44 and is sized to permitmovement therethrough of a fluid transfer device. (The proximal portionof the skirt 41, where the top surface 43 of the ledge 39 meets theinner surface 45 of the skirt, may be chamfered to deflect a misalignedfluid transfer device during penetration of the cap 30A-E, providedsufficient surface area remains on the top surface of the ledge foraffixing the frangible seal 32 thereto.) As shown in FIG. 7, the skirt41 includes a bottom surface 47 which may serve as an alternate locationfor affixing the frangible seal 32.

[0044] In an alternative core cap 31B embodiment shown in FIG. 5, theskirt 41 is eliminated from the core cap 31A structure shown in FIG. 4.In this embodiment, the frangible seal 32 may be affixed to either thebottom surface 42 or the top surface 43 of the ledge 39. However, sincethe skirt 41 aids in preventing fluids from leaking from a collectiondevice 10, it may be desirable to include an alternative fluid retainerfor this core cap 31B embodiment, such as a neoprene O-ring (not shown)fitted between the bottom surface 37 of the side wall 35 and an annulartop surface 23 of the vessel 20.

[0045] While the ledge 39 of the core cap 31B shown in FIG. 5 forms aflange structure having bottom and top surfaces 42, 43, this embodimentmay be modified so that the inner surface 40 of the side wall 35 isextended radially inward until an end surface 62 of the ledge and theinner surface of the side wall are co-extensive. In this modified formof the core cap 31B (not shown), the ledge 39 is defined by the bottomsurface 37 of the side wall 35, since the top surface 43 of the ledge iseliminated. Because the bore 44 of this embodiment is defined solely bythe inner surface 40 of the side wall 35, the frangible seal 32 must beaffixed to the bottom (or sole) surface 42 of the ledge 39.

[0046] A similar modification may be made to the preferred core cap 31A,whereby the inner surface 40 of the side wall 35 is extended radiallyinward until the inner surface 45 of the skirt 41 is co-extensive withthe inner surface of the side wall. This modified form of the core cap31A (not shown) eliminates the ledge 39, transforms the first and secondbores 44, 46 into a single bore, and requires that the frangible seal 32be affixed to the bottom surface 47 of the skirt 41. The disadvantage ofthese modified forms of the core caps 31A, 31B is that the alteration orelimination of the ledge 39 makes it is more difficult to maintain thefilter 33 within the cap 30A-E when the cap is penetrated by a fluidtransfer device. This problem may be overcome by adhering the filter 33to the side wall 35 of the cap 30A-E, the frangible seal 32 or theretaining means 34A-C, for example.

[0047] The core cap 31A-B may be integrally molded from a number ofdifferent polymer and heteropolymer resins, including, but not limitedto, polyolefins (e.g., high density polyethylene (“HDPE”), low densitypolyethylene (“LDPE”), a mixture of HDPE and LDPE, or polypropylene),polystyrene, high impact polystyrene and polycarbonate. A currentlypreferred material for forming the core cap 31A-B is an HDPE materialsold under the tradename Alathon M5370 by GE Polymerland ofHuntersville, N.C. Skilled artisans will readily appreciate that therange of acceptable cap resins will, in part, depend upon the nature ofthe resin used to form the vessel, since the properties of the resinsused to form these two components will affect how well the cap 30A-E andvessel 20 components of a collection device 10 can form a leak proofseal and the ease with which the cap can be securely screwed onto thevessel. As with the vessel 20 component, the material of the core cap31A-B should be essentially inert with respect to a fluid substance(including assay reagents) contained in the collection device 10 so thatthe material of the core cap does not significantly interfere with theperformance or results of an assay.

[0048] The core cap 31A-B is injection molded as a unitary piece usingprocedures well-known to those skilled in the art of injection molding.After the core cap 31A-B has been formed and cured for a sufficientperiod of time, the following components are added to the core cap inthe indicated manner and in any practicable order: (i) the frangibleseal 32 to the top surface 43 of the ledge 39 of either core cap 31A-B,to the bottom surface 42 of the ledge of the alternative core cap 31B,or to the bottom surface 47 of the skirt 41 of the preferred core cap31A; (ii) a filter 33 within the first bore 44; and (iii) a retainer34A-D to the annular top wall 48.

[0049] The frangible seal 32 is included to provide a substantiallyleak-proof barrier between the fluid contents of a collection device 10and the filter 33 contained in the first bore 44. For this reason, it isnot critical whether the frangible seal 32 is affixed to a surface 42,43 of the ledge 39 or to the bottom surface 47 of the skirt 41.According to a preferred embodiment of the present invention, the widthof the annular top surface 43 of the ledge 39 is about 0.08 inches (2.03mm), the thickness of the ledge (the distance between the top and bottomsurfaces 43, 42 of the ledge) is about 0.038 inches (0.97 mm), thecombined width of the annular bottom surface 42 of the ledge and theexposed bottom surface 37 of the side wall 35 is about 0.115 inches(2.92 mm), and the width of the annular bottom surface 47 of the skirt41 is about 0.025 inches (0.635 mm). The dimensions of these features ofthe core cap 31A-B may vary, of course, provided sufficient surface areaexists for affixing the frangible seal 32 to the core cap in asubstantially leak-proof manner.

[0050] The frangible seal 32 may be made of a plastic film (e.g., thinmonoaxially or biaxially oriented plastic film) or, preferably, of afoil (e.g., aluminum foil or other foil exhibiting low water vaportransmission), which can be affixed to a surface 42, 43 of the ledge 39or to the bottom surface 47 of the skirt 41 by means well known to thoseskilled in the art, including adhesives. The frangible seal 32 ispreferably not an integral component of the core cap 31A-B. If thefrangible seal 32 comprises a foil, it may further include acompatibilizer, such as a thin veneer of plastic applied to one or bothsurfaces of the foil, which will promote a substantially leak-proofattachment of the frangible seal to a surface of the core cap 31A-B withthe application of thermal energy. A heat sealer or heat inductionsealer may be used to generate the requisite thermal energy. (To avoidthe potentially deleterious effects of corrosion, it is recommended thatall portions of a metallic frangible seal 32 which might become exposedto the fluid contents of a collection device 10 during routine handlingbe coated with a plastic liner.) A TOSS Machine heat sealer (PackworldUSA; Nazareth, Pa.; Model No. RS242) is preferred for attaching thefrangible seal 32 to a surface 42, 43 of the ledge 39 or to the bottomsurface 47 of the skirt 41. Ultrasonic and radio frequency weldingprocedures known to those skilled in the art may also be used to affixthe frangible seal 32 to the core cap 31A-B.

[0051] To further promote attachment of the frangible seal 32 to thecore cap 31A-B, a surface 42, 43 of the ledge 39 or the bottom surface47 of the skirt 41 may be modified during injection molding of the corecap to include an energy director, such as an annular ring or series ofprotuberances. By limiting contact between the frangible seal 32 and aplastic surface of the ledge 39 or skirt 41, an energy director allowsthe frangible seal 32 to be affixed to the ledge or skirt in less timeand using less energy than would be required in its absence when anultrasonic welding procedure is followed. This is because the smallersurface area of the protruding energy director melts and forms a weldwith the plastic material of the frangible seal 32 more quickly than ispossible with a flat, unmodified plastic surface. An energy director ofthe present invention is preferably a continuous surface ring which istriangular in cross-section.

[0052] In order to facilitate the venting of air from within acollection device 10, the frangible seal 32 is preferably constructed sothat it tears when the seal is penetrated by a fluid transfer device,thereby forming air passageways 70 between the seal and the fluidtransfer device, as described in detail infra. To achieve this tearing,the seal 32 preferably includes a brittle layer comprised of a hardplastic material, such as a polyester. (See CHARLES A. HARPER, HANDBOOKOF PLASTICS, ELASTOMERS, AND COMPOSITES §1.7.13 (1997 3d ed.) for adiscussion of the properties of polyesters.) As shown in FIG. 8, thepreferred seal 32 of the present invention is a co-laminate thatincludes a foil layer, a heat seal layer and an intervening brittlelayer (Unipac; Ontario, Canada; Product No. SG-75M (excluding the pulpboard and wax layers typically included with this product)). With thispreferred seal 32, the foil layer is an aluminum foil having a thicknessof about 0.001 inches (0.0254 mm), the heat seal layer is a polyethylenefilm having a thickness of about 0.0015 inches (0.0381 mm), and thebrittle layer is a polyester having a thickness of about 0.0005 inches(0.0127 mm). Because this particular seal 32 design would have ametallic surface exposed to the contents of a collection device 10 aftersealing—if applied to the bottom surface 42 of the ledge 39 or to thebottom surface 47 of the skirt 41—it is preferred that this seal 32 beapplied to the top surface 43 of the ledge, as shown in FIGS. 6, 13, 15and 17. In this way, the cap 30A, C, D and E of these embodiments willhave no metallic surfaces exposed to the fluid contents of an associatedvessel 20. While the diameter of the seal 32 will depend upon thedimensions of the cap 30A-E, the presently preferred seal has a diameterof about 0.5 inches (12.70 mm).

[0053] An alternative frangible seal 32 embodiment is depicted in FIG.9, which shows a top foil layer with a lower combined brittle/heat seallayer comprised of an epoxy resin. The epoxy resin is selected for itsmechanical strength, which will promote formation of the desired airpassageways 70 discussed above when the material is penetrated by afluid transfer device. And, so that this seal 32 can be affixed to aplastic surface using a commonly practiced thermoplastic weldingprocedure, the epoxy layer further includes a compatibilizer dispersedwithin the epoxy resin, as shown in FIG. 9. A preferred compatibilizerof this seal 32 embodiment is a polyethylene.

[0054] As illustrated in the figures, the filter 33 is positioned withinthe first bore 44 above the ledge 39 and is incorporated to retard orblock the movement of an escaping aerosol or bubbles after the seal hasbeen pierced by a fluid transfer device. The filter 33 can also beconstructed to perform a wiping action on the outside of a fluidtransfer device as the fluid transfer device is being removed from acollection device 10. In a preferred mode, the filter 33 functions todraw fluids away from the outside of a fluid transfer device by means ofcapillary action. As used herein, however, the term “filter” refersgenerally to a material which performs a wiping function to removefluids present on the outside of a fluid transfer device and/or anabsorbing function to hold or otherwise sequester fluids removed fromthe outside of a fluid transfer device. For reasons discussed below, thefilters 33 of the present invention are composed of a material orcombination of materials having pores or interstices which admit thepassage of a gas. Examples of filter 33 materials which may be used withthe cap 30A-E of the present invention include, but are not limited to,pile fabrics, sponges, foams (with or without a surface skin), felts,sliver knits, Gore-Tex®, Lycra®, and other materials and blends, bothnatural and synthetic. These materials may also be mechanically orchemically treated to further improve the intended functions of thefilter 33. For example, napping may be used to increase the surface areaand, therefore, the fluid holding capacity of a filter 33. The materialof the filter 33 may also be pre-treated with a wetting agent, such as asurfactant, to lower the surface tension of a fluid present on an outersurface of a fluid transfer device. An acrylic binder might be used, forexample, to actually bind the wetting agent to the filter 33 material.Additionally, the filter 33 may include a super-absorbent polymer, (see,e.g., Sackmann et al., “Pre-Formed Super Absorbers with High SwellingCapacity,” U.S. Pat. No. 6,156,848), to prevent a fluid from escapingfrom a penetrated collection device 10.

[0055] To limit the unobstructed passage of air from within a collectiondevice 10 to the environment, the filter 33 is preferably made of aresilient material whose original shape is restored, or substantiallyrestored, as a fluid transfer device is being removed from thecollection device. This characteristic of the filter 33 is especiallyimportant when the fluid transfer device has a non-uniform diameter, asis the case with most pipette tips used with standard air displacementpipettes. Thus, materials such as pile fabric, sponges, foams and Lycraare preferred because they tend to quickly restore their original shapeafter exposure to compressive forces. Pile fabric is a particularlypreferred filter 33. An example of a preferred pile fabric is an acrylicmaterial having a thickness of about 0.375 inches (9.53 mm) which isavailable from Roller Fabrics of Milwaukee, Wis. as Part No. ASW112.Examples of other acceptable pile fabrics include those made of acrylicand polyester materials and which range in size from about 0.25 inches(6.35 mm) to about 0.3125 inches (7.94 mm). Such pile fabrics areavailable from Mount Vernon Mills, Inc. of LaFrance, S.C. as Part Nos.0446, 0439 and 0433. The filter 33 material is preferably inert withrespect to a fluid substance contained within the vessel 20.

[0056] Because the filter 33 is intended to remove fluid from theexterior of a fluid transfer device and to capture fluid in the form ofan aerosol or bubbles, it is best if the material and dimensions of thefilter material are chosen so that the filter does not become saturatedwith fluid during use. If the filter 33 does become saturated, fluid maynot be adequately wiped from the exterior of the fluid transfer deviceand bubbles may be produced as the fluid transfer device passes throughthe filter or as air is displaced from within the collection device 10.Thus, it is important to adapt the size and adsorptive properties of thefilter 33 in order to achieve adequate wiping and aerosol or bubblecontainment. Considerations when selecting a filter 33 will include thecap configuration, the shape and size of the fluid transfer device andthe nature and amount of fluid substance contained in the vessel 20,especially in view of the number of anticipated fluid transfers for agiven collection device 10. As the amount of fluid a filter 33 is likelyto be exposed to increases, the volume of the filter material or itsabsorptive properties may need to be adjusted so that the filter doesnot become saturated during use.

[0057] It is also important that the filter 33 be constructed andarranged in the cap 30A-E so that the flow of air out of the collectiondevice 10 remains relatively unimpeded as the cap is being penetrated bya fluid transfer device. In other words, the material of the filter 33and its arrangement within the cap 30A-E should facilitate the ventingof air displaced from within the collection device 10. Of course, thisventing property of the filter 33 needs to be balanced with therequirement that the filter material have sufficient density to trap anescaping aerosol or bubbles. Consequently, those skilled in the art willappreciate the need to select or design filter 33 materials havingmatrices that are capable of trapping an aerosol or bubbles, whilesimultaneously permitting air to be vented from within the collectiondevice 10 once the underlying seal 32 has been pierced by a fluidtransfer device.

[0058] As the figures show, the filter 33 is preferably sized to fitwithin the first bore 44 beneath the horizontal plane of the annular topwall 48. In a preferred cap 30A-E of the present invention, the filter33 also rests substantially or completely above the ledge 39, eventhough the seal 32 may be affixed to the bottom surface 47 of the skirt41, as illustrated in FIG. 7. To better ensure that the filter 33 is notsubstantially moved from its position within the first bore 44 byfrictional contact with a fluid transfer device penetrating or beingremoved from the cap 30A-E, the filter may be bound to the top surface43 of the ledge 39 or to the inner surface 40 of the side wall 35 usingan inert adhesive. Notwithstanding, the filter 33 is preferably a pilefabric which is snugly fitted in the first bore 44 and retained there bymeans of the seal 32 and the retainer 34A-D, without the use of anadhesive. In preferred cap 30A-E embodiments, the first bore 44 is about0.50 inches (12.70 mm) in diameter and has a height of about 0.31 inches(7.87 mm).

[0059] The material and configuration of the filter 33 should be suchthat it creates minimal frictional interference with a fluid transferdevice as it is being inserted into or withdrawn from the collectiondevice 10. In the case of a sponge or foam, for example, this mayrequire boring a hole or creating one or more slits in the center of thefilter 33 (not shown) which are sized to minimize frictionalinterference between the filter and a fluid transfer device, while atthe same time providing enough interference so that aerosol or bubbletransmission is limited and the wiping action is performed by the filtermaterial. If a pile fabric is employed as the filter 33, the pile fabricis preferably arranged in the manner shown in FIG. 10, such that thefree ends of individual fibers (shown as squiggles, but not specificallyidentified with a reference number) are oriented radially inwardlytoward the longitudinal axis 80 of the cap 30A-E and away from the pilefabric backing 49 which is in touching or fixed contact with the innersurface 40 of the side wall 35. When rolling the pile fabric forinsertion into the first bore 44, care should be taken not to wind thepile fabric so tightly that it will create excessive frictionalinterference with a fluid transfer device penetrating the cap 30A-E,thereby substantially impeding movement of the fluid transfer device. Aparticularly preferred pile fabric is available from Mount Vernon Mills,Inc. as Part No. 0446, which has a thickness of about 0.25 inches (6.35mm) and is cut to have a length of about 1.44 inches (36.58 mm) and awidth of about 0.25 inches (6.35 mm).

[0060] To immobilize the filter 33 within the first bore 44, the caps30A-E of the present invention include a retainer 34A-D positioned abovethe filter, preferably on the annular top wall 48. In a preferredembodiment shown in FIGS. 6 and 7, the retainer 34A is a solid,generally circular frangible seal which may be of the same or adifferent material than the frangible seal 32 positioned beneath thefilter 33. Preferably, the retainer 34A includes the same materials asthe preferred seal 32 described above, which comprises an aluminum foillayer, a polyester brittle layer, and a polyethylene heat seal layer(Unipac; Ontario, Canada; Product No. SG-75M (excluding the pulp boardand wax layers typically included with this product)). This retainer 34Acan be applied to the annular top wall 48 with a heat sealer or heatinduction sealer in the same manner that the seal 32 is applied to asurface 42, 43 of the ledge 39 or to the bottom surface 47 of the skirt41. Like the preferred seal 32, the preferred retainer 34A has a foillayer thickness of about 0.001 inches (0.0254 mm), a brittle layerthickness of about 0.0005 inches (0.0127 mm), and a heat seal layerthickness of about 0.0015 inches (0.0381 mm). The diameter of thepreferred retainer is about 0.625 inches (15.88 mm). Of course, thediameter of this preferred retainer 34A may vary and will depend uponthe dimensions of the annular top wall 48.

[0061] As illustrated in FIG. 11, the retainer 34A may be adapted tofacilitate penetration by including one or more series of perforations50 which extend radially outwardly from a center point 51 of theretainer. The center point 51 of these radiating perforations 50 ispreferably positioned to coincide with the expected entry point of afluid transfer device. Also contemplated by the present invention areother types of adaptations that would reduce the tensile strength of theretainer 34A, including creases, score lines or other mechanicalimpressions applied to the material of the retainer. The sameadaptations may also be made to the seal 32, provided the seal willcontinue to exhibit low water vapor transmission characteristics afterthe collection device 10 is exposed to normal shipping and storageconditions.

[0062] Besides providing a means for keeping the filter 33 fixed withinthe first bore 44 prior to and during a fluid transfer, a seal retainer34A can protect the underlying filter from external contaminants priorto penetration of the cap 30A. Moreover, a cap 30A designed tocompletely seal the filter 33 within the first bore 44 may be sterilizedprior to use by, for example, gamma irradiation. Additionally, theretainer 34 of such a cap 30A could be wiped with a disinfectant or theentire collection device 10 could be irradiated with ultraviolet lightprior to penetration to facilitate a sterile fluid transfer.

[0063] In those instances where the potential presence of contaminantson the filter would not be of significant concern, however, the retainermay comprise a foil ring, for example, which includes a centrallylocated hole which is sized to receive a fluid transfer device. Asillustrated in FIG. 12, a cap 30C having a retainer 34B with a centrallylocated hole 52 could aid in retaining the filter 33 within the firstbore 44, while at the same time limiting the number of surfaces that afluid transfer device would have to pierce in order to fully penetratethe cap. To retain the filter 33 within the first bore 44, the diameterof the hole 52 would have to be smaller than the diameter of the filterwhen the hole and the filter are substantially axially aligned.

[0064] Another cap 30D embodiment is illustrated in FIGS. 13 and 14. Theretainer 34C of this cap 30D is a plastic disc which includes acentrally located hole 53 sized to receive a fluid transfer device. Thedisc 34C may be affixed to the annular top wall 48 by means of anadhesive or welded by heat, ultrasound or other appropriate weldingmethod known to skilled artisans. Alternatively, the annular top wall 48may be modified to include a seat 54 which is sized to receive the disc34C in, for example, a frictional or snap fit. While this particular cap30D embodiment does not provide the filter 33 with a completely sealedenvironment, the disc retainer 34C can nevertheless function to containthe filter 33 within the first bore 44 during transport of thecollection device 10, as well as during a fluid transfer. If it isimportant to protect the filter 33 from potential contaminants prior touse, then the cap 30D of this embodiment could further include a seal,such as the frangible seal 34A described supra, affixed to a top 55 or abottom surface 56 of the disc 34C so that the hole 53 is fully andsealably covered. As illustrated in FIGS. 15 and 16, one such seal 34Dcould include a tab 57 for easy removal. With this design, the seal 34Dof a cap 30E could be removed just before penetration of the cap with afluid transfer device, allowing the filter 33 to be protected fromexternal contaminants immediately prior to use. An advantage of this cap30E over, for example, the cap 30A-B embodiments shown in FIGS. 6 and 7is that penetration of the cap will require less force since there isonly one seal 32, as opposed to the two seals 32, 34A of thoseembodiments, that the fluid transfer device needs to pierce.

[0065] When a cap 30A-E of the present invention is pierced by a fluidtransfer device 90 which is used to retrieve at least a portion of afluid sample 100 contained in a collection device 10, as shown in FIG.17, one or more tears are preferably formed in the frangible seal 32and, if comprised of a frangible seal, the retainer 34A. As FIG. 18illustrates, these tears in the frangible seal form air passageways 70which facilitate the venting of air displaced from within a collectiondevice 10 as the fluid transfer device 90 enters the interior space 11(defined as the space below the cap 30A-E and within inner surfaces 24,25 of the side wall 22 and a bottom wall 26 of the vessel 20) of thecollection device 10. By providing means for venting air displaced fromwithin a collection device 10, the volume accuracy of fluid transfers(e.g., pipetting) will likely be improved. While a variety of fluidtransfer devices can be used with the present invention, includinghollow metal needles and conventional plastic pipette tips havingbeveled or flat tips, a preferred fluid transfer device is the Genesisseries 1000 μl Tecan-Tip (with filter), available fromEppendorf-Netherler-Hinz GmbH of Hamburg, Germany as Part No. 612-513.Fluid transfer devices of the present invention are preferably able topenetrate the frangible seal 32 with the application of less than about3 pounds force (13.34 N), more preferably less than about 2 pounds force(8.90 N), even more preferably less than about 1 pound force (4.45 N),and most preferably less than about 0.5 pounds force (2.22 N).

[0066] The insertion force, which is the total or additive forcerequired to pierce all penetrable surfaces of a cap 30A-E according tothe present invention (i.e., the frangible seal 32, the filter 33 and,optionally, the retainer 34A) with a fluid transfer device, ispreferably less than about 8 pounds force (35.59 N), more preferablyless than about 6.5 pounds force (28.91 N), even more preferably lessthan about 5 pounds force (22.24 N), and most preferably less than about4.5 pounds force (20.02 N). The withdrawal force, which is the forcerequired to completely withdraw a fluid transfer device from thecollection device 10 after the cap 30A-E has been completely penetrated,is preferably less than about 4 pounds force (17.79 N), more preferablyless than about 3 pounds force (13.34 N), even more preferably less thanabout 2 pounds force (8.90 N), and most preferably less than about 1pound force (4.45 N). The forces exerted on the fluid transfer device asit is being withdrawn from a collection device 10 should be minimized toavoid stripping the fluid transfer device from, for example, themounting probe of a vacuum pipette. Insertion and withdrawal forces canbe determined using conventional force measurement instruments, such asa motorized test stand (Model No. TCD 200) and digital force gauge(Model No. DFGS-50) available from John Chatillon & Sons, Inc. ofGreensboro, N.C.

[0067] A cap 30A-E according to the present invention is generallyprovided in combination with a fluid-holding vessel 20 as components ofa collection device 10. The cap 30A-E and vessel 20 of the collectiondevice 10 can be joined by means of mated threads which allow the cap tobe screwed, snapped or otherwise frictionally fitted onto an outersurface 21 of the side wall 22 at the open end of the vessel. When thecap 30A-E is frictionally fitted onto the vessel 20, the bottom surface37 of the side wall 35 of the cap is preferably in contact with theannular top surface 23 of the vessel to provide an interference fit,thereby facilitating the essentially leak-proof seal discussed above.The cap 30A-E can be modified to further improve resistance of thecollection device 10 to leaking by providing an annular seal bead 58 toan outer surface 59 of the skirt 41, as shown in FIG. 4. If the sealbead 58 is included, it should be sized so that it will be in frictionalcontact with the inner surface 24 of the side wall 22 of the vessel 20but will not substantially interfere with joining of the cap 30A-E andvessel. The annular center 60 of the preferred seal bead 58 is about0.071 inches (1.80 mm) from the bottom surface 37 of the side wall 35and extends radially outwardly about 0.0085 inches (0.216 mm) from theouter surface 59 of the skirt 41, where the thickness of the skirt 41above the seal bead 58 is about 0.052 inches (1.32 mm). The skirt 41preferably includes a beveled base 61 below the seal bead 58 tofacilitate joining of the cap 30A-E and vessel 20. In a preferredembodiment, the skirt 41 extends downward a vertical distance of about0.109 inches (2.77 mm) from the annular center 60 of the seal bead 58 tothe bottom surface 47 of the skirt and uniformly decreases in thicknessfrom about 0.0605 inches (1.54 mm) to about 0.025 inches (0.635 mm)between the annular center of the seal bead and the bottom surface ofthe skirt. The second bore 46 of this preferred embodiment has adiameter of about 0.340 inches (8.64 mm) and a height of about 0.218inches (5.54 mm).

[0068] When provided as a component of a kit, the collection device 10of the present invention preferably includes a specimen retrieval devicefor obtaining a sample to be analyzed, where the specimen retrievaldevice has preferably been sized to fit within the interior space 11 ofthe collection device after the cap 30A-E and vessel 20 have beenjoined. A preferred specimen retrieval device is a swab, such as theswab disclosed by Pestes et al., “Cell Collection Swab,” U.S. Pat. No.5,623,942. This particular swab is preferred because it is manufacturedto include a score line which is positioned on the stem of the swab,allowing the swab to be manually snapped in two after a specimen hasbeen obtained, leaving the lower, specimen-bearing portion of the swabentirely inside the vessel 20 component of the collection device 10.When the specimen is being transported to a clinical laboratory, thecollection device 10 also preferably includes a transport medium forpreserving the sample prior to analysis. Transport mediums are wellknown in the art and will vary depending upon the sample type andwhether cell lysis prior to analysis is necessary.

[0069] Additionally, a kit according to the present invention mayinclude instructions recorded in a tangible form (e.g., contained onpaper or an electronic medium) which explain how the components of thecollection device 10 are to be manipulated when obtaining a fluid sampleor how the cap 30A-E is to be secured onto the vessel 20 prior totransporting the collection device to a clinical laboratory.Alternatively, or in addition to, the instructions may detail properpipetting techniques for retrieving at least a portion of the samplefrom the collection device 10 prior to analysis. These instructions mayinclude information about types of fluid transfer devices that can beused to penetrate the cap 30A-E, positioning of a fluid transfer devicefor penetrating the cap and/or the amount of force needed to penetratethe cap. The instructional materials may also detail proper use of thecollection device when the sample is to be exposed to reagents andconditions useful for amplifying a nucleic acid sequence targeted fordetection.

[0070] Amplification prior to detection is particularly desirable indiagnostic assays where the initial population of targeted nucleic acidsequences in a sample is expected to be relatively small, makingdetection of the targeted nucleic acid sequences more difficult. Thereare many procedures for amplifying nucleic acids which are well known inthe art, including, but not limited to, the polymerase chain reaction(PCR), (see, e.g., Mullis, “Process for Amplifying, Detecting, and/orCloning Nucleic Acid Sequences,” U.S. Pat. No. 4,683,195),transcription-mediated amplification (TMA), (see, e.g., Kacian et al.,“Nucleic Acid Sequence Amplification Methods,” U.S. Pat. No. 5,399,491),ligase chain reaction (LCR), (see, e.g., Birkenmeyer, “Amplification ofTarget Nucleic Acids Using Gap Filling Ligase Chain Reaction,” U.S. Pat.No. 5,427,930), and strand displacement amplification (SDA), (see, e.g.,Walker, “Strand Displacement Amplification,” U.S. Pat. No. 5,455,166).The particular reagents (e.g., enzymes and primers) and conditionsselected by practitioners will vary depending upon the particularnucleic acid sequence being targeted for detection and the specificamplification procedure to be followed. Those skilled in the art ofnucleic acid diagnostics, however, will be able to select appropriatereagents and conditions for amplifying a specific targeted nucleic acidsequence following a particular amplification procedure without havingto engage in undue experimentation.

[0071] While the present invention has been described and shown inconsiderable detail with reference to certain preferred embodiments,those skilled in the art will readily appreciate other embodiments ofthe present invention. Accordingly, the present invention is deemed toinclude all modifications and variations encompassed within the spiritand scope of the following appended claims.

What we claim is:
 1. A penetrable cap comprising: a closed side wallhaving an inner surface, an outer surface, a top surface and a bottomsurface; attachment means for fixing the cap to an open-ended vessel insealing engagement; a ledge extending radially inwardly from the innersurface of the side wall of the cap and having a top surface, a bottomsurface and an end surface, the end surface of the ledge defining anaperture sized to receive a fluid transfer device, wherein the innersurface of the side wall of the cap and the top surface of the ledgedefine a bore; a frangible seal for preventing the passage of a fluidfrom an interior space of the vessel defined by the side wall and abottom wall of the vessel into the bore, the seal being affixed to thetop or bottom surface of the ledge; filtering means for impeding orpreventing the release of an aerosol or bubbles from the interior spaceof the vessel into the atmosphere, the filtering means being positionedsubstantially within the bore; and retaining means for containing thefiltering means within the bore.
 2. The cap of claim 1, wherein the sidewall, the flange and the ledge of the cap are comprised of a moldedplastic and form a unitary piece.
 3. The cap of claim 2, wherein theside wall of the cap is generally cylindrical.
 4. The cap of claim 3,wherein the outer surface of the cap includes serrations to facilitatemanual gripping of the cap.
 5. The cap of claim 1, wherein the seal isaffixed to the top surface of the ledge.
 6. The cap of claim 1, whereinthe seal comprises a foil.
 7. A collection device comprising the cap ofclaim
 1. 8. The collection device of claim 7 in packaged combinationwith at least one of a transport medium and a specimen retrieval device.9. A method for removing a fluid substance from a collection device, themethod comprising the steps of: a) penetrating the cap of claim 7 with afluid transfer device such that air passageways are formed between thefluid transfer device and the seal, thereby permitting air to be ventedfrom the interior space of the vessel; b) drawing at least a portion ofthe fluid substance into the fluid transfer device; and c) removing thefluid transfer device from the collection device.
 10. The method ofclaim 9, wherein the fluid transfer device is a plastic pipette tip foruse with an air displacement pipette, and wherein the total forcerequired to penetrate the cap with the pipette tip in step a) is lessthan about 8 pounds force.
 11. The method of claim 9, wherein the fluidtransfer device is a plastic pipette tip for use with an airdisplacement pipette, and wherein the total force required to penetratethe cap with the pipette tip in step a) is less than about 6.5 poundsforce.
 12. The method of claim 9, wherein the fluid transfer device is aplastic pipette tip for use with an air displacement pipette, andwherein the total force required to penetrate the cap with the pipettetip in step a) is less than about 5 pounds force.
 13. The method ofclaim 9, wherein the fluid transfer device is a plastic pipette tip foruse with an air displacement pipette, and wherein the total forcerequired to penetrate the cap with the pipette tip in step a) is lessthan about 4.5 pounds force.
 14. The method of claim 9 furthercomprising the step of exposing at least a portion of the fluidsubstance removed from the collection device in step c) to nucleic acidamplification reagents and conditions.
 15. A penetrable cap comprising:a closed side wall having an inner surface, an outer surface, a topsurface and a bottom surface; attachment means for fixing the cap to anopen-ended vessel in sealing engagement; a ledge extending radiallyinwardly from the inner surface of the side wall of the cap and having atop surface, a bottom surface and an end surface, the end surface of theledge defining an aperture sized to receive a fluid transfer device,wherein the inner surface of the side wall of the cap and the topsurface of the ledge define a first bore; a skirt depending from thebottom surface of the ledge, the skirt having an inner surface, an outersurface and a bottom surface, wherein the inner surface of the skirtdefines a second bore having a diameter or width smaller than that ofthe first bore; a frangible seal for preventing the passage of a fluidfrom an interior space of the vessel defined by the side wall and abottom wall of the vessel into the first bore, the seal being affixed tothe top surface of the ledge or to the bottom surface of the skirt;filtering means for impeding or preventing the release of an aerosol orbubbles from the interior space of the vessel into the atmosphere, thefiltering means being positioned substantially within the first bore;and retaining means for containing the filtering means within the firstbore.
 16. The cap of claim 15, wherein the side wall, the flange, theledge and the skirt of the cap are comprised of a molded plastic andform a unitary piece.
 17. The cap of claim 16, wherein the side wall andthe skirt of the cap are generally cylindrical.
 18. The cap of claim 17,wherein the outer surface of the cap includes serrations to facilitatemanual gripping of the cap.
 19. The cap of claim 15, wherein the seal isaffixed to the top surface of the ledge.
 20. The cap of claim 15,wherein the seal comprises a foil.
 21. A collection device comprisingthe cap of claim
 15. 22. The collection device of claim 21 in packagedcombination with at least one of a transport medium and a specimenretrieval device.
 23. A method for removing a fluid substance from acollection device, the method comprising the steps of: a) penetratingthe cap of claim 21 with a fluid transfer device such that airpassageways are formed between the fluid transfer device and the seal,thereby permitting air to be vented from the interior space of thevessel; b) drawing at least a portion of the fluid substance into thefluid transfer device; and c) removing the fluid transfer device fromthe collection device.
 24. The method of claim 23, wherein the fluidtransfer device is a plastic pipette tip for use with an airdisplacement pipette, and wherein the total force required to penetratethe cap with the pipette tip in step a) is less than about 8 poundsforce.
 25. The method of claim 23, wherein the fluid transfer device isa plastic pipette tip for use with an air displacement pipette, andwherein the total force required to penetrate the cap with the pipettetip in step a) is less than about 6.5 pounds force.
 26. The method ofclaim 23, wherein the fluid transfer device is a plastic pipette tip foruse with an air displacement pipette, and wherein the total forcerequired to penetrate the cap with the pipette tip in step a) is lessthan about 5 pounds force.
 27. The method of claim 23, wherein the fluidtransfer device is a plastic pipette tip for use with an airdisplacement pipette, and wherein the total force required to penetratethe cap with the pipette tip in step a) is less than about 4.5 poundsforce.
 28. The method of claim 23 further comprising the step ofexposing at least a portion of the fluid substance removed from thecollection device in step c) to nucleic acid amplification reagents andconditions.
 29. A penetrable cap comprising: a closed side wall havingan inner surface, an outer surface, a top surface and a bottom surface;attachment means for fixing the cap to an open-ended vessel in sealingengagement; a ledge extending radially inwardly from the inner surfaceof the side wall of the cap and having a top surface, a bottom surfaceand an end surface, the end surface of the ledge defining an aperturesized to receive a fluid transfer device, wherein the inner surface ofthe side wall of the cap and the top surface of the ledge define a firstbore; a skirt depending from the bottom surface of the ledge, the skirthaving an inner surface, an outer surface and a bottom surface, whereinthe inner surface of the skirt defines a second bore having a diameteror width smaller than that of the first bore; a first frangible seal forpreventing the passage of a fluid from an interior space of the vesseldefined by the side wall and a bottom wall of the vessel into the firstbore, the seal being affixed to the top surface of the ledge or to thebottom surface of the skirt; a filter for impeding or preventing therelease of an aerosol or bubbles from the interior space of the vesselinto the atmosphere, the filter being positioned substantially withinthe first bore; and a second frangible seal for retaining the filterwithin the first bore.
 30. The cap of claim 29, wherein the side wall,the flange, the ledge and the skirt of the cap are comprised of a moldedplastic and form a unitary piece.
 31. The cap of claim 30, wherein theside wall and the skirt of the cap are generally cylindrical.
 32. Thecap of claim 31, wherein the outer surface of the cap includesserrations to facilitate manual gripping of the cap.
 33. The cap ofclaim 29, wherein the skirt has an outer surface which includes a sealbead which is in frictional contact with an inner surface of the sidewall of the vessel when the cap is fitted onto the open end of thevessel.
 34. The cap of claim 29, wherein the first seal is affixed tothe top surface of the ledge.
 35. The cap of claim 29, wherein each ofthe first and second seals comprises a foil.
 36. The cap of claim 29,wherein the filter comprises a material selected from the groupconsisting of a pile fabric, a sponge, a foam, a felt, a sliver knit,Gore-Tex® and Lycra®.
 37. The cap of claim 36, wherein the filtercomprises a pile fabric.
 38. A penetrable cap comprising: a closed sidewall having an inner surface, an outer surface, a top surface and abottom surface; attachment means for fixing the cap to an open-endedvessel in sealing engagement; a ledge extending radially inwardly fromthe inner surface of the side wall of the cap and having a top surface,a bottom surface and an end surface, the end surface of the ledgedefining an aperture sized to receive a fluid transfer device, whereinthe inner surface of the side wall of the cap and the top surface of theledge define a first bore; a skirt depending from the bottom surface ofthe ledge, the skirt having an inner surface, an outer surface and abottom surface, wherein the inner surface of the skirt defines a secondbore having a diameter or width smaller than that of the first bore; afrangible seal for preventing the passage of a fluid from an interiorspace of the vessel defined by the side wall and a bottom wall of thevessel into the first bore, the seal being affixed to the top surface ofthe ledge or to the bottom surface of the skirt; a filter for impedingthe release of an aerosol or bubbles from the interior space of thevessel into the atmosphere, the filter being positioned substantiallywithin the first bore; and a foil ring affixed to the top surface of theside wall of the cap, wherein the ring has a centrally located holewhich is sized to receive the fluid transfer device and which issubstantially axially aligned with the first and second bores.
 39. Thecap of claim 38, wherein the side wall, the flange, the ledge and theskirt of the cap are comprised of a molded plastic and form a unitarypiece.
 40. The cap of claim 39, wherein the side wall and the skirt ofthe cap are generally cylindrical.
 41. The cap of claim 40, wherein theouter surface of the cap includes serrations to facilitate manualgripping of the cap.
 42. The cap of claim 38, wherein the skirt has anouter surface which includes a seal bead which is in frictional contactwith an inner surface of the side wall of the vessel when the cap isfitted onto the open end of the vessel.
 43. The cap of claim 38, whereinthe seal is affixed to the top surface of the ledge.
 44. The cap ofclaim 38, wherein the seal comprises a foil.
 45. The cap of claim 38,wherein the filter comprises a material selected from the groupconsisting of a pile fabric, a sponge, a foam, a felt, a sliver knit,Gore-Tex® and Lycra®.
 46. The cap of claim 45, wherein the filtercomprises a pile fabric.
 47. A penetrable cap comprising: a closed sidewall having an inner surface, an outer surface, a top surface and abottom surface; attachment means for fixing the cap to an open-endedvessel in sealing engagement; a ledge extending radially inwardly fromthe inner surface of the side wall of the cap and having a top surface,a bottom surface and an end surface, the end surface of the ledgedefining an aperture sized to receive a fluid transfer device, whereinthe inner surface of the side wall of the cap and the top surface of theledge define a first bore; a skirt depending from the bottom surface ofthe ledge, the skirt having an inner surface, an outer surface and abottom surface, wherein the inner surface of the skirt defines a secondbore having a diameter or width smaller than that of the first bore; afirst frangible seal for preventing the passage of a fluid from aninterior space of the vessel defined by the side wall and a bottom wallof the vessel into the first bore, the seal being affixed to the topsurface of the ledge or to the bottom surface of the skirt; a filter forimpeding or preventing the release of an aerosol or bubbles from theinterior space of the vessel into the atmosphere, the filter beingpositioned substantially within the first bore; and a disc affixed tothe top surface of the side wall of the cap, wherein the disc has a holeformed therein which is sized to receive the fluid transfer device andwhich is substantially axially aligned with the first and second bores.48. The cap of claim 47, wherein the disc is comprised of a plastic, andwherein the side wall, the flange, the ledge and the skirt of the capare comprised of a molded plastic and form a unitary piece.
 49. The capof claim 48, wherein the side wall and the skirt of the cap aregenerally cylindrical.
 50. The cap of claim 49, wherein the outersurface of the cap includes serrations to facilitate manual gripping ofthe cap.
 51. The cap of claim 47, wherein the skirt has an outer surfacewhich includes a seal bead which is in frictional contact with an innersurface of the side wall of the vessel when the cap is fitted onto theopen end of the vessel.
 52. The cap of claim 47, wherein the top surfaceof the side wall of the cap includes a shelf sized to receive the discin a frictional fit.
 53. The cap of claim 47 further comprising a secondseal affixed to a top surface or a bottom of the disc and which coversthe hole formed in the disc.
 54. The cap of claim 53, wherein the secondseal is affixed to the top surface of the disc and includes a tab forremoval.
 55. The cap of claim 53, wherein the second seal comprises afrangible foil.
 56. The cap of claim 47, wherein the filter comprises amaterial selected from the group consisting of a pile fabric, a sponge,a foam, a felt, a sliver knit, Gore-Tex® and Lycra®.
 57. The cap ofclaim 56, wherein the filter comprises a pile fabric.
 58. A penetrablecap comprising: a generally cylindrical side wall having an innersurface, an outer surface, a top surface and a bottom surface; a flangedepending from the bottom surface of the side wall of the cap and havingan inner surface adapted to grip an outer surface of a generallycylindrical side wall of an open-ended vessel; a ledge extendingradially inwardly from the inner surface of the side wall of the cap andhaving a top surface, a bottom surface and an annular end surface, theend surface of the ledge defining an aperture sized to receive a fluidtransfer device, wherein the inner surface of the side wall of the capand the top surface of the ledge define a first bore; a generallycylindrical skirt depending from the bottom surface of the ledge, theskirt having an inner surface, an outer surface and a bottom surface,wherein the inner surface of the skirt defines a second bore having adiameter smaller than that of the first bore, wherein the skirt has anouter surface which includes an annular seal bead which is in frictionalcontact with an inner surface of the side wall of the vessel when thecap is fitted onto the open end of the vessel, and wherein the sidewall, the flange, the ledge and the skirt of the cap are comprised of amolded plastic and form a unitary piece; a first frangible seal forpreventing the passage of a fluid from an interior space of the vesseldefined by the side wall and a bottom wall of the vessel into the firstbore, the seal being affixed to the top surface of the ledge; a filterfor impeding or preventing the release of an aerosol or bubbles from theinterior space of the vessel into the atmosphere, the filter beingpositioned substantially within the first bore; and a second frangibleseal for retaining the filter within the first bore.
 59. The cap ofclaim 58, wherein each of the first and second seals comprises a foil.60. The cap of claim 59, wherein the filter comprises a pile fabric. 61.A method for removing a fluid substance contained in a closed systemcomprising a cap and a fluid-holding vessel, the method comprising thesteps of: a) penetrating a first frangible seal affixed to the cap witha fluid transfer device such that air passageways are formed between thefluid transfer device and the first seal; b) penetrating a secondfrangible seal affixed to the cap and axially aligned below the firstseal with the fluid transfer device such that air passageways are formedbetween the fluid transfer device and the second seal, therebypermitting air to be vented from an interior space of the system; c)drawing at least a portion of the fluid substance contained in thevessel into the fluid transfer device; and d) removing the fluidtransfer device from the system.
 62. The method of claim 61, whereineach of the first and second seals comprises a foil.
 63. The method ofclaim 61 further comprising the step of passing the fluid transferdevice through a filter contained within the cap and interposed betweenthe first and second seals.
 64. The method of claim 63, wherein thefilter comprises a material selected from the group consisting of a pilefabric, a sponge, a foam, a felt, a sliver knit, GoreTex® and Lycra®.65. The method of claim 64, wherein the filter comprises a pile fabric.66. The method of claim 61, wherein the fluid transfer device is aplastic pipette tip for use with an air displacement pipette, andwherein the total force required to penetrate the first and second sealsis less than about 8 pounds force.
 67. The method of claim 61, whereinthe fluid transfer device is a plastic pipette tip for use with an airdisplacement pipette, and wherein the total force required to penetratethe first and second seals is less than about 6.5 pounds force.
 68. Themethod of claim 61, wherein the fluid transfer device is a plasticpipette tip for use with an air displacement pipette, and wherein thetotal force required to penetrate the first and second seals is lessthan about 5 pounds force.
 69. The method of claim 61, wherein the fluidtransfer device is a plastic pipette tip for use with an airdisplacement pipette, and wherein the total force required to penetratethe first and second seals is less than about 4.5 pounds force.
 70. Themethod of claim 61 further comprising the step of exposing at least aportion of the fluid substance removed from the collection device instep d) to nucleic acid amplification reagents and conditions.
 71. Themethod of claim 61, wherein the penetrating steps are performed by anautomated instrument.
 72. A method for depositing a substance in aclosed system comprising a cap and an open-ended vessel, the methodcomprising the steps of: a) penetrating a first frangible seal affixedto the cap with a substance transfer device; b) penetrating a secondfrangible seal affixed to the cap and axially aligned below the firstseal with the substance transfer device; c) depositing one or moresubstances in the vessel; and d) removing the substance transfer devicefrom the system.
 73. The method of claim 72 further comprising the stepof passing the substance transfer device through a filter containedwithin the cap and interposed between the first and second seals. 74.The method of claim 72, wherein at least one of the substances depositedin the vessel is a fluid.
 75. The method of claim 74, wherein the fluidis a reagent for performing a diagnostic assay.